Can we deprecate "D-style Variadic Functions"

[deadalnix via Digitalmars-d]

On Friday, 27 March 2015 at 14:24:47 UTC, Shammah Chancellor 
wrote:
> On 2015-03-26 01:04:03 +0000, Freddy said:
>
>> On Thursday, 26 March 2015 at 00:11:05 UTC, Dicebot wrote:
>>> On Wednesday, 25 March 2015 at 22:12:04 UTC, Freddy wrote:
>>>> "D-style Variadic Functions" found 
>>>> here:http://dlang.org/function.html seem entirely out 
>>>> classed by Variadic Function Templates. Can we deprecate 
>>>> them?
>>> 
>>> Those are two different concepts with different trade-offs. 
>>> Using variadic templates adds template bloat. Using D-style 
>>> variadics requires RTTI (and small overhead for it). It is up 
>>> to library/application writer to decide what is best in his 
>>> case.
>> 
>> My ploblem is that Variadic Function shouldn't be builtin the 
>> language. They are rarely need and can be abstracted into a 
>> library. Something like this:
>> ```
>> import core.stdc.stdlib: alloca;
>> import std.stdio;
>> template VariadicFunction(alias Imp){
>> 	auto VariadicFunction(T...)(T args){
>> 		enum size=T.length * TypeInfo.sizeof;
>> 		auto rtti=cast(TypeInfo[])(alloca(size)[0..size]);
>> 		foreach(i,type;T){
>> 			rtti[i]=typeid(type);
>> 		}
>> 		//auto data=&args; bug? doesn't work
>> 		void* data;
>> 		{
>> 			size_t datasize;//T.sizeof doesn't work
>> 			foreach(type;T){
>> 				datasize+=type.sizeof;
>> 			}
>> 			data=alloca(datasize);
>> 			size_t inc;
>> 			foreach(v;args){
>> 				*cast(typeof(v)*)(data+inc)=v;
>> 				inc+=v.sizeof;
>> 			}
>> 		}
>> 		Imp(data,rtti);
>> 	}
>> }
>> 
>> private void rtVariadicImp(void* vars,scope const TypeInfo[] 
>> rtinfo){
>> 	writeln(*cast(int*)vars);
>> 	writeln(rtinfo);
>> }
>> 
>> alias rtVariadic=VariadicFunction!(rtVariadicImp);
>> 
>> void main(){
>> 	rtVariadic(1,'a');
>> }
>> ```
>
> I disagree, and your example does not get rid of the template 
> bloat.  That does in fact instantiate a template for every set 
> of argument types.
>
> -Shammah

To be fair, this is most likely going to be inlined an ditched 
away with any decent optimizer.